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  • Research Article
  • Open Access

Turbo-per-Tone Equalization for ADSL Systems

EURASIP Journal on Advances in Signal Processing20052005:581826

  • Received: 9 October 2003
  • Published:


We study the equalization procedure in discrete multitone (DMT)-based systems, in particular, in DMT-based ADSL systems. Traditionally, equalization is performed in the time domain by means of a channel shortening filter. Shifting the equalization operations to the frequency domain, as is done in per-tone equalization, increases the achieved bitrate by 5–10%. We show that the application of the turbo principle to per-tone equalization can provide significant additional gains. In the proposed receiver structure, referred to as a "turbo-per-tone equalization" structure, equalization and decoding are performed in an iterative fashion. Equalization is done by means of a linear minimum mean squared error (MMSE) equalizer, using a priori information. We give a description of an efficient implementation of such an equalizer in the per-tone structure. Simulations show that we obtain a bitrate increase of 12–16% compared to the original per-tone equalization-based receiver structure.

Keywords and phrases

  • ADSL
  • multicarrier modulation
  • turbo equalization

Authors’ Affiliations

ESAT/SCD, Katholieke Universiteit Leuven, Kasteelpark Arenberg 10, Heverlee, 3001, Belgium